US2417824A

US2417824A - Load transfer unit

Info

Publication number: US2417824A
Application number: US511225A
Authority: US
Inventors: James H Jacobson
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-11-22
Filing date: 1943-11-22
Publication date: 1947-03-25
Anticipated expiration: 1964-03-25

Description

March 25, 1947. H, JACOBSON 2,4724

LOAD TRANSFER UNIT Filed' Nov. 22. 194

l 727776 Sig/605.5019

Patented Mar. 25, 1947 vUNlTED STATES PATENT OFFICEv LOAD TRANSFER UNIT James Jacobson, Chicago, Ill.

Application November 22, 1943, Serial No. 511,225

LMllaims. l

This invention is directed to a load transference unit, the sections of which are adapted to be embedded within concrete road slabs whichv present their faces on opposite sides of a road joint, and thus serve as mountings for a dowel which bridges the gap and serves to transmit load stresses thereover. The sections of the unit are designed to afford a firm and effective anchorage within the concrete without the provision of Widely extended wings, fins or other projections which introduce excessive irregularities in the surface contour of the unit sections and which may under varying conditions of stress and resultant vibration act as focal points in the initiation of disintegrating or funneling action. The unit sections of the present invention on the contrary are so designed that downwardly directed pressures will be resisted by the upwardly facing walls of the sections in such a manner as to eliminate any considerable tendency toward horizontal displacement, while the under wall surfaces, which are not subjected to downwardly directed pressures, are of conoidal, inwardly enlarging, formation to afford effective anchorage which is supplemented only by relatively small lateral iins which do not in any substantial degree interrupt the smoothly rounded contour of the bodies of the unit sections.

Further objects and details will appear from a description of the invention in conjunction with the accompanying drawings wherein,

Figure l is a side elevation of the unit installed as a contraction joint;

Fig. 2 is a longitudinal sectional View showing the unit installed as an expansion joint;

Fig. 3 is an inner end elevation of one of the unit sections; Y

Fig. 4 is a top view of one of the unit sections; and

Fig. 5 is an inner end View of the thin metal cap.

The unit as a whole consists of two sections ID, which are preferably malleable iron castings, and since the two are duplicates, a description of one will suffice for both. The sections stand in opposed relation to one another on opposite sides of the joint gap with their forward ends exposed in ush relation to the face of the concrete slab within which the section is embedded.

Each section is integrally formed to provide an inwardly extending body portion ii, embedded save for its forward face, inthe concrete, a vertical standard I2 having its inner face and edges embedded, and a backwardly extending foot I3 having its upper face and edges embedded and its base in contact with the sub-grade.

The body portion is of reduced circular cross section at its forward end I4 and enlarged circular cross section at its inner end i5, but with the axes of successive cross sections lying in an obliquely downwardly and backwardly extend ing line, which gives to the body a conoidal formation presenting a horizontal medial prole I5 along its upper surface and an oblique medial profile Il along its lower medial surface so that the contour of the body as a Whole gives it the characteristics of a wedge, progressively enlarging toward its inner end but presenting an upper surface which along its longitudinal center line is normal to downwardly directed pressure lines. Moreover, the contour of the entire upper surface is such as to minimize the wedging tendency to produce longitudinal displacement under vertical stress, while the under surface which is free from vertical stress, is so configured as to increase its anchoring effect.

The under surface of the body being obliquely disposed to the horizontal in substantial degree along its medial profile when embedded, affords substantial resistance to longitudinal displacement while the inner Wall surface of the body is planate and without lateral extensions which, if present, might tend, under vibration, to dig into and abrade or wear away the adjacent concrete.

At the forward end of the body are two symmetrically disposed laterally projecting fins I8, the front ends of which lie flush with the forward face of the body while the inner ends taper down and merge into the curved wall surface near the middle on each side.

The body of each unit section is provided from end to end with a bore I9 which runs parallel with the upper medial profile, and the bores of the unit sections are aligned to receive a dowel 20 which is of a length to extend at each end beyond the companion bodies, even when separated to the degree shown in Fig. 1. Each of the bodies at its inner end is shouldered concentrically with the bore to provide a reduced flange 2|, and onto one of the flanges so formed, is tted a cap 22 of thin metal having a cylindrical body 23 of a size to provide a sliding fit around'the protruding end of the dowel and of a length slightly greater than the maximum protruson of the dowel, so as to provide within the concrete of one of the slabs a void or cavity adapted to permit movement of the dowel within said void to allow for expansion and contraction of the concrete due to changes in temperature.

The cap is closed at its inner end 24 and offset at its forward end 25 to closely t upon the flange 2| and in order to temporarily hold the dowel and the unit section in proper relation to one another, the cap is indented at 2B to provide a fragile abutment for the end of the dowel at a point well in advance of the closed end of the Gap.

body, exclusive of the fins I8. The standard lis of slightly increasing width toward its lower end where it merges into the inwardly vextei'idirig foot, and at the points of juncture, between the body and foot respectively, the standard is reenforced by

webs

21 and 28 respectively.

The foot terminates inwardly in a broadened end portion 29 oiset at the shoulders 30 and notched in its end edge 2l.

When the unit is to be employed as a contraction joint the parts are adjusted as in Fig. 1 with a wide gap between the opposed forward faces of the unit sections and the ,uncapped end of the dowel protruding but slightly from the associated body section. In this case in the event of contraction of the gap, due to expansion of the concrete, vthe capped end of the dowel will be free to move within the recess afforded wit-hin the cap, while the opposite uneapped end of the dowel will move in unison with the unit section through which it is entered. The indentation `26 in the fragile wall of the cap affords merely` a temporary obstruction which will be sheared away as the dowel slides toward the end of the cavity afforded by the cap.

d When the unit is used as an expansion joint, the forward faces of the unit sections will initially lie close together on opposite sides of a narrow gap and withV the uncapped end of the dowel protruding to a substantial degree. In such case, as the concrete contracts, and the gap increases in width, the capped end of the dowel will permit the associated unit section to move along the dowel to the necessary extent and until the end of the dowel in relation to the end ofthe cap, occupies the position indicated by dotted lines in Fig. 2. j

The conoidal formation of the body serves to anchor the unit section rmly within the concrete in such a way as to resist any tendency to move forward towardthe gap while the iat inner end of the body which is 1of maximum diameter presents va widely extended surface to `resist movement in the oppositedirectiomso thatwidely extended anchoring wings lor the likeare unnecessary. y

Moreover, Athe openjended bores through the two unit'sections permit the use of dowels of vany desiredjlength since the-degree of protrusion uof the 'ends lof the d owel 'from the bodies of the unit` sections can be varied tol-meet diverse conditions. Although I have described a dowel-which is formed separately from the respective sections and which when' lnuseis immovably held within one of the sections, it is obvious that the dowel mightbe permanently united therewith without materially modifying the structure -or function of the device `as a whole. Where I'employ the terin comdair do not intend to limit the claims to ajbody 'structure in which the cross ldiameter`-a.t"fa`.ri'y point istruly circular since the term is intended to dei-lne and include ovat'. elliptical or similar forms which involve a de-l parture from true circularity.

I claim:

l. In a load transference device, a unit section adapted to be located at a road joint and consisting of a unitary casting comprising a substantially horizontal base, a vertical standard rising from the base, 2and a substantially horizontal body extending inwardly from the upper end of the standard, said unit section presenting a continuous vertical surface from top to bottom in flush relation` with the surface of a slab and having a continuous horizontal bottom surface extending inwardly from said vertical surface, said body being provided with a, longitudinal bore and of noidal formation progressively enlarging from the front end towards the rear end and presenting a substantially horizontal upper medial profile and an obliquely 'downwardly and rearwardly extending lower -medial profile, vand a dowel slidable within the body and carried thereby and extending beyond the ends of the body.

2. In a load transference device, a unit section adapted to be located at a road joint and consisting of a unitary casting comprising a -substantially horizontal base, a vertical standard rising from the base, and a-substantially horizontal-body extending inwardly from the `upper end of the standard, said unit section presenting a continuous vertical surface from top Vto bottom in ush relation with the surface of a slab and having a continuous horizontal bottom surface extending inwardly frorn said vertical surface, said body being `provided with a longitudinal bore -and of conoidal formation progressively enlarging from the front end towards the rear end and presenting a substantially horizontal upper medial profile and an obliquely downwardly and rearwardly extending lower medial profile, said body being provided at its inner end with an annular longitudinally projecting flange arranged concentric with the bore of the body, a cylindrical cap having an offset `outer end tted on said annular flange, said cap being closed at its inner end, and a dowel slidable in the bore of the body and in said cap.

3. In a load transference device, a unit section adapted to belocated at a road joint and consisting of a unitary casting comprising a substantially horizontal base, a vertical standard rising from the lbase, and a substantially'horizontal body extending inwardly from the upper end of the standard, said unit -section presenting a continuous 4vertical surface `from top to bottom in lflush relation with the surface of a slab-andhaving a continuous horizontal bottom fsurface extending inwardly from said vertical surface, said body being provided with a longitudinal fbore'an'd'of conoidal formation progressively enlarging from the front end towards the rear fend andlpresenting a substantially horizontal upper 4medial profile and an obliquely downwardlyand rearwardly/'extending lowerrnedial'prole,*said body lbeing provided 'at its inner end with an 'annular longitudinally `projecting'flange arranged concentric with the bore of thelb'ody, a cylindrical cap'having an offset 'outer end fitted von said annular flange, saidcapibeingclos'edat its inner`end,a'nd a dowel slidable in thebore ofthe body andA in said cap, said capbeing V-provided with an interior frangible abutmentinitially engaging one endfof the dowel to position the same duringpouring of concrete and adapted to -be -displacedvbythe dowel to permit sliding movement of the dowel in the cap.

4. In a load transference device, a unit section adapted to be located at a road joint and consisting of a unitary casting comprising a substantially horizontal base, a vertical standard rising from the base, and a substantially horizontal body extending inwardly from the upper end of the standard, said unit section presenting a continuous vertical surface from top to bottom in flush relation with the surface of a slab and having a continuous horizontal bottom surface extending inwardly from said vertical surface, said body being provided with a longitudinal bore and of conoidal formation progressively enlarging from 15 2,208,454

the front end towards the rear end, and a dowel slidable within the body and carried thereby and extending beyond the ends of the body.

JAMES H. JACOBSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,263,150 Westcott Nov. 18, 1941 1,982,695 Robertson Dec. 4, 1934 850,097 Perkins Apr. 9, 1907 Geyer July 16, 1940